Mostly the the lack of fun factor or satisfaction compared to early Dragon Quest games; I found the game boring. I can’t really say specifically what elements made it feel that way, since I haven’t picked up the game since the PS2 generation and I kind of forget it.
Some things I specifically recall was we kept chasing around this clown enemy I didn’t care about (Dull Magus, a fitting name) for like 40 hours. The world was overly spread out and slow to move around. The mechanics took too long to use. The encounter rate was brutal in that game, worse than any other DQ game. It was like Phantasy Star bad.
The dungeons were obnoxiously long and excruciatingly bland - worse than the worst from Witcher 3 and Xenoblade games; and I’ll note that these games still don’t have nearly as much dungeon stuff. Only Xenoblade 1 had a significant amount of it; Witcher 3 and Xenoblade Chronicles X have hardly any, only that the little that’s there is the worst part of those games...
Not that I hate dungeons absolutely, I like the dungeons in some games like Chronological Trigger (I’m just going to leave that English auto-correct spelling), Dragon Quest 5, Breath of the Wild, and Link to the Past. But I had no love for DQ6-8 dungeons.
In short - The things I remember most from DQ 8 were its slowness (everything from battles, to moving around, menus, etc...), obnoxious dungeons, and obnoxious encounter rates. I don’t recall the story at all, other than Dull Magus. I don’t even remember why he was evil, only that he was an angry clown with an irritating laugh that the main characters were annoyed by.
Well thankfully DQXI doesn't have random encounters. Like IX, enemies are on the map easy to sea. Traversal is not slow even on foot. It's a well-paced game. Dungeons don't feel too long with the exception of a couple. Tho you do revisit a couple of them late game. DQXI might feel a tad overwhelming at first as the areas seem huge but they are not as big as you think first time through. It has a wonderful cast. The one downside and it is optional but the 3rd act is kind of tedious. I did do it for the "real" ending plus I didn't want to explore a ruined world but if you wish just YT it after playing the game. It's really cool. Battles/menus were fairly fast in regular battles. Boss battles are typical DQ boss battles. Pull up a chair. Thankfully this is maybe the least grindy game in the series. I only did grinding when I felt like it. I never felt forced. If I lost a battle I did something wrong...with the exception of the act 3 boss having a trick they don't do a good job of telling you. Making him from impossible to very managable. I don't know if plus or minus for you. This game is not very difficult.
Plus this game has a photo mode you can dance in and you can pet all the dogs in the game.
Bite my shiny metal Cockpit!